Asymmetric air rudder for hovercraft inner and outer loop type air propellers

Abstract

A hovercraft inner and outer annular channel type air propeller is an asymmetric air rudder, three rudder blades are arranged in parallel relative to the air propeller, the cross section of each rudder blade is in an aircraft wing shape, the middle rudder blade is a forward rudder blade consistent with the side floating force direction, and the rudder blades on the two sides are reverse rudder blades opposite to the side floating force direction. According to the asymmetric air rudder for the hovercraft inner and outer loop type air propellers, the rudder blade is essentially a vertical wing, the wing generates corresponding lift force when having a wing type positive angle of attack, the wing does not generate lift force or the generated lift force is extremely small when having a wing type negative angle of attack, and no obvious influence is generated on navigation; therefore, through the shapes and the arrangement directions of the three rudder blades, the side floating force generated by the air propeller can be counteracted when the hovercraft sails positively, so that the sailing stability of the hovercraft is effectively improved, and enough steering force can be provided during steering by utilizing the lift force difference of the rudder blades.

Description

Technical Field

[0001] The invention relates to an air cushion craft, in particular to an air rudder used in conjunction with inner and outer loop air propellers on a small air cushion craft. Background Art

[0002] A hovercraft is a high-speed ship that uses the principle of surface effect to form an air cushion so that the hull can be separated from the supporting surface to achieve navigation. The hovercraft mainly relies on two airflows in different directions to achieve navigation. The airflow at the bottom forms an air cushion to lift the hull, and the airflow at the rear serves as the thrust. For large hovercraft, these two airflows can be generated by different engines; for small hovercraft, due to the limited space in the hull, generally only a single engine can be used, and the airflow can be directed to different directions in conjunction with a deflector that distributes the airflow. The inner and outer ring duct air propeller is a device used for small hovercraft.

[0003] The inner and outer ring duct air propeller divides the duct into two parts, the inner ring guides part of the airflow to the outside to provide propulsion, and the outer ring guides the airflow into the boost chamber to provide cushion lift. Among them, the hovercraft requires the airflow entering the boost chamber to be as smooth and uniform as possible, while the airflow generated by the air propeller is spiral, and there is a problem of inconsistent air intake on the left and right. Therefore, it is necessary to set a guide vane on one side to change the direction of the airflow, but this will generate additional side drift force, such as Figure 1 As shown in P in the figure, the heading stability of small hovercraft is poor, which greatly affects its speed improvement and popularity. Summary of the invention

[0004] The object of the present invention is to provide an asymmetric air rudder for inner and outer loop air propellers of a hovercraft which can reduce the influence of lateral drift force, so as to improve the navigation stability of a small hovercraft.

[0005] The asymmetric air rudder for the inner and outer ring air propellers of the hovercraft described in the present invention comprises three rudder blades arranged opposite to the air propeller, and the cross-sectional shape of the rudder blades is an airplane airfoil; the three rudder blades are arranged in parallel, and the middle rudder blade is a forward rudder blade consistent with the direction of the side drift force, and the rudder blades on both sides are reverse rudder blades opposite to the direction of the side drift force.

[0006] Furthermore, three rudder blades are rotatably mounted on the air propeller and are arranged opposite to the air outlet of the air propeller.

[0007] Furthermore, there is a rudder bracket fixedly mounted on the air propeller, and three rudder blades are mounted on the rudder bracket through a linkage, and there is also a driver that drives the three rudder blades to rotate synchronously through the linkage.

[0008] Furthermore, the airfoil of the rudder blade satisfies the following formula:

[0009] The present invention discloses an asymmetric air rudder for inner and outer loop air propellers of an air cushion vehicle. The three rudder blades are arranged opposite to the air propellers on the air cushion vehicle, and are arranged in sequence along a straight line with a reverse rudder blade, a forward rudder blade, and a reverse rudder blade at intervals. When the air cushion vehicle is sailing forward, the rudder blades do not deflect, and the three rudder blades all generate lift. The forward rudder blade and one of the reverse rudder blades have lifts in opposite directions and cancel each other out, and the remaining rudder blades interact with the lateral drift force and cancel each other out. When the air cushion vehicle turns left, the three rudder blades swing in the same direction at the same angle, and the airfoil of the middle forward rudder blade is negative. Angle of attack, no lift is generated, the airfoils of the reverse rudder blades on both sides are at a positive angle of attack, which will generate lift. These lifts can generate steering force while offsetting the side drift force, and constitute a steering torque with the fluid resistance suffered by the hovercraft, thereby achieving a left turn; when the hovercraft turns right, the three rudder blades swing synchronously in the other direction, so that the airfoils of the reverse rudder blades on both sides are converted into a negative angle of attack, and no lift is generated, while the airfoil of the middle positive rudder blade is converted into a positive angle of attack and generates lift. The lift of the rudder blade will constitute a steering force together with the side drift force, and constitute a steering torque with the fluid resistance suffered by the hovercraft, thereby achieving a right turn. The asymmetric air rudders used for the inner and outer ring air propellers of this type of hovercraft have rudder blades that are essentially vertical wings. The wings will generate corresponding lift when the airfoil has a positive angle of attack, and will not generate lift or will generate very little lift when the airfoil has a negative angle of attack, which will not have a significant impact on navigation. Therefore, through the shape and setting direction of the three rudder blades, the side drift force generated by the air propeller can be offset when the hovercraft is sailing, thereby effectively improving the stability of the hovercraft's navigation, and the lift difference of the rudder blades can be used to provide sufficient steering force when turning. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of an air propeller and the side drift force it generates.

[0011] Figure 2 It is a schematic diagram of the structure of an asymmetric air rudder for inner and outer ring air propellers of a hovercraft.

[0012] Figure 3 yes Figure 2 The schematic diagram of the structure of the three rudder blades in the direction A of the asymmetric air rudder for the inner and outer ring air propellers of the hovercraft is shown.

[0013] Figure 4 , 5 This is a diagram of the relative positions of the three rudder blades and the air propeller when the hovercraft is turning. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial...), then the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0016] If there are descriptions involving "first" or "second" in the embodiments of the present invention, the descriptions of "first" or "second" are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0017] The invention provides an asymmetric air rudder for inner and outer loop air propellers of a hovercraft.

[0018] The asymmetric air rudder for the inner and outer ring air propellers of the hovercraft of this embodiment comprises three rudder blades 2 arranged opposite to the air propeller 1, and the cross-sectional shape of the rudder blades is an aircraft airfoil; the three rudder blades are arranged in parallel, and the middle rudder blade is a forward rudder blade 3 consistent with the direction of the side drift force, and the rudder blades on both sides are reverse rudder blades 4 opposite to the direction of the side drift force.

[0019] like Figure 2 , 3 As shown, the rudder blade is essentially a vertical wing. The wing will generate corresponding lift when the airfoil has a positive angle of attack, and will not generate lift or the generated lift is extremely small when the airfoil has a negative angle of attack, which will not have a significant impact on navigation; the three rudder blades are rotatably mounted on the air propeller and are arranged opposite to the air outlet of the air propeller, and the three rudder blades are spaced apart in a straight line direction, which are a reverse rudder blade, a forward rudder blade, and a reverse rudder blade, respectively.

[0020] When the hovercraft is moving forward, Figure 3As shown in the figure, the rudder blade does not deflect, and all three rudder blades generate lift L. The lift generated by the upper reverse rudder blade and the middle forward rudder blade are in opposite directions and cancel each other out. The lower reverse rudder blade will interact with the side drift force P and cancel it out. When the hovercraft turns left, Figure 4 As shown in the figure, the three rudder blades swing in the same direction at the same angle. The airfoil of the middle positive rudder blade is a negative angle of attack and does not generate lift. The airfoils of the upper and lower reverse rudder blades are positive angles of attack and will generate lift L. These lifts can offset the side drift force P and generate steering force, which together with the fluid resistance of the hovercraft form a steering torque, thereby achieving left turn. When the hovercraft turns right, Figure 5 As shown, the three rudder blades swing synchronously in the other direction, so that the airfoils of the reverse rudder blades on both sides are transformed into negative angles of attack and no lift is generated, while the airfoil of the middle positive rudder blade is transformed into a positive angle of attack and generates lift L. The lift of the rudder blade will form a steering force together with the side drift force, and form a steering torque together with the fluid resistance of the hovercraft, thereby realizing a right turn.

[0021] The asymmetric air rudder for the inner and outer ring air propellers of the hovercraft has a rudder bracket 5 fixedly mounted on the air propeller 1, and three rudder blades 2 are mounted on the rudder bracket through a linkage 6. There is also a driver (not shown) that drives the three rudder blades to rotate synchronously through the linkage, thereby ensuring the accuracy of the synchronous rotation of the three rudder blades and simplifying the structural complexity to better adapt to the use of small hovercraft.

[0022] The described hovercraft inner and outer ring air propeller uses an asymmetric air rudder, and the airfoil of the rudder blade satisfies the following formula:

[0023] Where, L is the lift of the rudder blade; C L is the lift coefficient of the rudder blade; ρ a is the air density; V is the slip velocity of the duct on the air propeller; A is the projected area of ​​the rudder blade.

[0024] The steering force when the hovercraft turns left is 2Lcosθ-F (θ is the airfoil angle of attack of the rudder blade, that is, the limited yaw angle, and F is the yaw force when the hovercraft is sailing), and the steering force when turning right is Lcosθ+F. To ensure that the steering forces on both sides of the hovercraft are consistent, it is necessary to ensure that 2Lcosθ-F=Lcosθ+F, that is, L=2F / cosθ; when sailing forward, it is necessary to ensure that L+F=2L, that is, L=F; when turning, it is in a large angle of attack state, usually within the stall angle of attack range, and the lift coefficient increases with the increase of the angle of attack.

[0025] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An asymmetric air rudder for an inner and outer loop air propeller of a hovercraft, characterized in that: It comprises three rudder blades (2) arranged opposite to an air propeller (1), the cross-sectional shape of the rudder blades being an aircraft airfoil; the three rudder blades are arranged in parallel, the middle rudder blade is a forward rudder blade (3) in the same direction as the side drift force, and the rudder blades on both sides are reverse rudder blades (4) in the opposite direction to the side drift force.

2. The asymmetric air rudder for the inner and outer loop air propeller of the hovercraft according to claim 1, characterized in that: The three rudder blades (2) are rotatably mounted on the air propeller (1) and are arranged opposite to the air outlet of the air propeller.

3. The asymmetric air rudder for the inner and outer loop air propeller of the hovercraft according to claim 2, characterized in that: There is a rudder bracket (5) fixedly mounted on the air propeller (1), three rudder blades (2) are mounted on the rudder bracket via a linkage (6), and there is also a driver for driving the three rudder blades to rotate synchronously via the linkage.

4. The asymmetric air rudder for the inner and outer loop air propeller of the hovercraft according to claim 1, characterized in that: The airfoil of the rudder blade satisfies the following formula: In the formula, is the lift of the rudder blade; is the lift coefficient of the rudder blade; is the air density; is the slip velocity of the duct on the air propeller; is the projected area of ​​the rudder blade.

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